Persistent indication of acknowledgement resources

ABSTRACT

A user equipment is configured with at least two collections of uplink resources to be used for transmitting control information to a communication network. The UE receives an assignment of radio resources to be used for receiving a downlink transmission from a base station of the communication network. The UE receives an acknowledgement resource indication, ARI, indicating one of the configured collections of uplink resources to be used for transmitting control information associated with the DL transmission. Further, the UE transmits the control information to the base station on at least a subset of the indicated collection of UL resources. In example embodiments, the indicated collection of uplink resources comprises a plurality of selectable uplink resource sets. The control information is transmitted on one of the uplink resource sets which corresponds to an operational state of the communication network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/524,197, filed on Nov. 11, 2021, which is a continuation of U.S.patent application Ser. No. 16/068,250, filed on Jul. 5, 2018, issued asU.S. Pat. No. 11,265,115 on Mar. 1, 2022, which is a 35 U.S.C. § 371national stage application of PCT International Application No.PCT/SE2018/050392 filed on Apr. 18, 2018, which in turns claims domesticpriority to U.S. Provisional Patent Application No. 62/501,754, filed onMay 5, 2017, the disclosures and contents of which are incorporated byreference herein in their entireties

TECHNICAL FIELD

Disclosed herein are techniques for transmitting and receiving controlinformation associated with a wireless link. In particular, there isproposed a mechanism for indicating radio resources for acknowledgementfeedback that may allow the communication parties to adapt therepresentation of the acknowledgement feedback.

BACKGROUND

Wireless networks standardized by Third Generation Partnership Long TermEvolution (3GPP LTE) implement ARQ (Automatic Repeat Request) orhybrid-ARQ (HARQ), wherein HARQ also includes forward error correction.In networks of this type, transmitting devices are required to sendacknowledgement feedback to the receiving device indicative of a resultof decoding a transport block or codeword (ACK/NACK or ACK/NAKfeedback). The ACK/NACK related to downlink (DL) transmissions istransmitted on the uplink (UL). The feedback is used to trigger fastretransmissions. The signaling aspects of HARQ in LTE are specifiedinter alia in clause 10 of 3GPP Technical Specification 36.213.

The physical uplink control channel (PUCCH) in 3GPP New Radio (NR),including the acknowledgement feedback mechanism, is currently beingdeveloped.

It has been agreed that NR will support explicit resource allocation. Ithas been agreed that the Downlink Control Information (DCI) message canindicate the slot in which to report HARQ feedback. In addition to thetiming the UE also needs to know the exact PUCCH resource. It has beenagreed to at least support PUCCH resources configured by higher layers,and DCI indicates which of the configured resources to use. FIG. 1A is asimplified time-frequency diagram, in which a DL transmission is shownscheduled in slot n and an Acknowledgement Resource Indication (ARI)included in the DCI message requests the HARQ feedback in resource R1.DCI furthermore contains an indication, denoted “T=1”, which requeststhe HARQ feedback to be transmitted in slot n+1. It is recalled that anNR slot corresponds to 7 or 14 Orthogonal Frequency-DivisionMultiplexing (OFDM) symbols; at 15-kHz subcarrier spacing, a slot with 7OFDM symbols occupies 0.5 ms. Concerning NR terminology, reference ismade to 3GPP TR 38.802 v14.0.0 or later versions.

In FIG. 1B, another scheduling example is shown where a UE is scheduledin subsequent slots where DL transmissions are scheduled. Due to lack ofPUCCH opportunities, e.g. no UL opportunities, HARQ feedback for allthree shown transmissions is requested in slot n+3. More precisely, theACK/NACK timing indicator included in the DCI messages points for alltransmissions to slot n+3. The instances of ARI included in the DCIspoint at different PUCCH resources to avoid collisions.

It is currently expected that NR will support at least the followingPUCCH formats:

Short PUCCH Format 1: 1 symbol, payload 1-2 bits

Short PUCCH Format 2: 1 symbol, >2 bits

Short PUCCH Format 3: 2 symbol, 1-2 bits

Short PUCCH Format 4: 2 symbol, >2 bits

Long PUCCH Format 1: 4-14 symbols, 1-2 bits

Long PUCCH Format 2: 4-14 symbols, >2 to 10 or few 10 bits

Long PUCCH Format 3: 4-14 symbols, >10 for few 10 bits

Since the formats occupy different amounts of UL resources, the ARI inNR may be required to indicate a wide range of values. Rather thanaccepting the comparatively large signaling overhead that this wouldrepresent if implemented by a straightforward approach, the techniquesproposed herein seek to simplify the ARI and limit its contribution tothe total overhead.

SUMMARY

The invention proposes devices, methods, computer programs and computerprogram products addressing the needs and problems outlined in thepreceding section.

In a first aspect, there is provided a method of transmitting controlinformation to a communication network, the method being implemented ina user equipment and comprising:

-   -   being configured with at least two collections of UL resources        to be used for transmitting control information to the        communication network;    -   receiving an assignment of radio resources to be used for        receiving a DL transmission from a base station of the        communication network;    -   receiving an ARI indicating one of the configured collections of        UL resources to be used for transmitting control information        associated with the DL transmission; and    -   transmitting the control information to the base station on at        least a subset of the indicated collection of UL resources,        wherein the indicated collection of UL resources comprises a        plurality of selectable UL resource sets and the control        information is transmitted on one of the UL resource sets which        corresponds to an operational state of the communication        network. The base station may be included in a communication        system which further includes a host computer configured to        transmit user data to the user equipment via the base station.

In a second aspect, there is provided a UE comprising a radio interfaceand processing circuitry configured to:

-   -   allow the UE to be configured with at least two collections of        UL resources to be used for transmitting control information to        the communication network;    -   receive an assignment of radio resources to be used for        receiving a DL transmission from a base station of the        communication network;    -   receive an ARI indicating one of the configured collections of        UL resources to be used for transmitting control information        associated with the DL transmission; and    -   transmit the control information to the base station on at least        a subset of the indicated collection of UL resources,        wherein the indicated collection of UL resources comprises a        plurality of selectable UL resource sets and the control        information is transmitted on one of the UL resource sets which        corresponds to an operational state of the communication        network. The base station may be included in a communication        system which further includes a host computer configured to        transmit user data to the user equipment via the base station.

In a third aspect, there is provided a method of receiving controlinformation at a base station of a communication network, the methodcomprising:

-   -   obtaining a configuration of at least two collections of UL        resources to be used for receiving control information from user        equipments in coverage of the communication network;    -   assigning radio resources to be used for transmitting a DL        transmission to a user equipment;    -   transmitting an ARI to the user equipment, the ARI indicating        one of the configured collections of UL resources to be used for        receiving control information associated with the DL        transmission; and    -   receiving the control information from the user equipment on at        least a subset of the indicated collection of UL resources,        wherein the indicated collection of UL resources comprises a        plurality of selectable UL resource sets and the control        information is received on one of the UL resource sets which        corresponds to an operational state of the communication        network. The base station may be included in a communication        system which further includes a host computer configured to        transmit user data to the user equipment via the base station.

In a fourth aspect, there is provided a base station for operating in acommunication network comprising a radio interface and processingcircuitry configured to:

-   -   obtain a configuration of at least two collections of UL        resources to be used for receiving control information from user        equipments in coverage of the communication network;    -   assign radio resources to be used for transmitting a DL        transmission to a user equipment;    -   transmit an ARI to the user equipment, the ARI indicating one of        the configured collections of UL resources to be used for        receiving control information associated with the DL        transmission; and    -   receive the control information from the user equipment on at        least a subset of the indicated collection of UL resources,        wherein the indicated collection of UL resources comprises a        plurality of selectable UL resource sets and the control        information is received on one of the UL resource sets which        corresponds to an operational state of the communication        network. The base station may be included in a communication        system which further includes a host computer configured to        transmit user data to the user equipment via the base station.

The dependent claims define example embodiments. It is noted that theinvention relates to all combinations of features even if received inmutually different claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will now be described with reference to theaccompanying drawings, on which:

FIGS. 1A and 1B discussed above are time-frequency diagrams illustratingDL control channel resources, DL data resources and UL control channelresources;

FIG. 2 schematically illustrates a telecommunication network which isoptionally connected, via an intermediate network, to a host computer;

FIG. 3 is a generalized block diagram of a host computer communicatingvia a base station with a user equipment over a partially wirelessconnection;

FIGS. 4 and 5 are flowcharts illustrating methods implemented in acommunication system including a host computer, a base station and auser equipment;

FIG. 6 is a flowchart illustrating a method implemented in a userequipment; and

FIG. 7 is a flowchart illustrating a method implemented in a basestation.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Within the context of the present disclosure, the term “communicationnetwork” or short “network” may particularly denote a collection ofnodes or entities, related transport links, and associated managementneeded for running a service, for example a telephony service or apacket transport service. Depending on the service, different node typesor entities may be used to realize the service. The communicationnetwork is owned by a network operator or operated on the networkoperator's behalf and offers the implemented services to itssubscribers. Typical examples of a communication network are radioaccess network, such as WLAN/Wi-Fi™ and cellular networks like 2G/GSM,3G/UMTS, 4G/LTE and NR.

Within the context of the present disclosure, each of the terms “userequipment” (UE) and “wireless communication device” refers to a devicefor instance used by a person for his or her personal communication. Itcan be a telephone-type of device, for example a telephone or a SIPphone, cellular telephone, a mobile station, cordless phone, or apersonal digital assistant type of device like laptop, notebook, notepadequipped with a wireless data connection, or table computer. The UE mayalso be associated with non-humans like animals, plants, or evenmachines, and may then be configured for machine-type communication,machine-to-machine communication, device-to-device communication orsidelink. A UE may be equipped with a SIM (Subscriber Identity Module)comprising unique identities such as IMSI (International MobileSubscriber Identity) and/or TMSI (Temporary Mobile Subscriber Identity)associated with a subscriber using the UE. The presence of a SIM withina UE customizes the UE uniquely with a subscription of the subscriber.

Within the context of the present disclosure, each of the terms “basestation” and “wireless access node” refers to a node of a radio accessnetwork that is used as interface between land-based transport links andradio-based transport links, wherein the radio-based transport linkinterfaces directly with a UE. In different generations of cellularcommunication, the term base station may refer to a BTS, a NodeB, aneNodeB or gNB. In WLAN/Wi-Fi™ architecture, a base station refers to anAccess Point (AP).

The invention may be put to use in any node in a network that implementstransmitter or receiver functionality. One typical implementation is ina UE and relates to processing of a downlink transport block withACK/NACK feedback transmitted on uplink.

With reference to FIG. 2 , in accordance with an embodiment, acommunication system includes a telecommunication network 210, such as a3GPP-type cellular network, which comprises an access network 211, suchas a radio access network, and a core network 214. The access network211 comprises a plurality of base stations 212 a, 212 b, 212 c, such asNBs, eNBs, gNBs or other types of wireless access points, each defininga corresponding coverage area 213 a, 213 b, 213 c. Each base station 212a, 212 b, 212 c is connectable to the core network 214 over a wired orwireless connection 215. A first user equipment (UE) 291 located incoverage area 213 c is configured to wirelessly connect to, or be pagedby, the corresponding base station 212 c. A second UE 292 in coveragearea 213 a is wirelessly connectable to the corresponding base station212 a. While a plurality of UEs 291, 292 are illustrated in thisexample, the disclosed embodiments are equally applicable to a situationwhere a sole UE is in the coverage area or where a sole UE is connectingto the corresponding base station.

Optionally, the telecommunication network 210 is itself connected to ahost computer 230, which may be embodied in the hardware and/or softwareof a standalone server, a cloud-implemented server, a distributed serveror as processing resources in a server farm. The host computer 230 maybe under the ownership or control of a service provider, or may beoperated by the service provider or on behalf of the service provider.The connections 221, 222 between the telecommunication network 210 andthe host computer 230 may extend directly from the core network 214 tothe host computer 230 or may go via an optional intermediate network220. The intermediate network 220 may be one of, or a combination ofmore than one of, a public, private or hosted network; the intermediatenetwork 220, if any, may be a backbone network or the Internet; inparticular, the intermediate network 220 may comprise two or moresub-networks (not shown).

The communication system of FIG. 2 as a whole enables connectivitybetween one of the connected UEs 291, 292 and the host computer 230. Theconnectivity may be described as an over-the-top (OTT) connection 250.The host computer 230 and the connected UEs 291, 292 are configured tocommunicate data and/or signaling via the OTT connection 250, using theaccess network 211, the core network 214, any intermediate network 220and possible further infrastructure (not shown) as intermediaries. TheOTT connection 250 may be transparent in the sense that theparticipating communication devices through which the OTT connection 250passes are unaware of routing of upstream and downstream communications.For example, a base station 212 may not or need not be informed aboutthe past routing of an incoming downstream communication with dataoriginating from a host computer 230 to be forwarded (e.g., handed over)to a connected UE 291. Similarly, the base station 212 need not be awareof the future routing of an outgoing upstream communication originatingfrom the UE 291 towards the host computer 230.

Example implementations, in accordance with an embodiment, of the UE,base station and host computer discussed in the preceding paragraphswill now be described with reference to FIG. 3 . In a communicationsystem 300, a host computer 310 comprises hardware 315 including acommunication interface 316 configured to set up and maintain a wired orwireless connection with an interface of a different communicationdevice of the communication system 300. The host computer 310 furthercomprises processing circuitry 318, which may have storage and/orprocessing capabilities. In particular, the processing circuitry 318 maycomprise one or more programmable processors, application-specificintegrated circuits, field programmable gate arrays or combinations ofthese (not shown) adapted to execute instructions. The host computer 310further comprises software 311, which is stored in or accessible by thehost computer 310 and executable by the processing circuitry 318. Thesoftware 311 includes a host application 312. The host application 312may be operable to provide a service to a remote user, such as a UE 330connecting via an OTT connection 350 terminating at the UE 330 and thehost computer 310. In providing the service to the remote user, the hostapplication 312 may provide user data which is transmitted using the OTTconnection 350.

The communication system 300 further includes a base station 320provided in a telecommunication system and comprising hardware 325enabling it to communicate with the host computer 310 and with the UE330. The hardware 325 may include a communication interface 326 forsetting up and maintaining a wired or wireless connection with aninterface of a different communication device of the communicationsystem 300, as well as a radio interface 327 for setting up andmaintaining at least a wireless connection 370 with a UE 330 located ina coverage area (not shown in FIG. 3 ) served by the base station 320.The communication interface 326 may be configured to facilitate aconnection 360 to the host computer 310. The connection 360 may bedirect or it may pass through a core network (not shown in FIG. 3 ) ofthe telecommunication system and/or through one or more intermediatenetworks outside the telecommunication system. In the embodiment shown,the hardware 325 of the base station 320 further includes processingcircuitry 328, which may comprise one or more programmable processors,application-specific integrated circuits, field programmable gate arraysor combinations of these (not shown) adapted to execute instructions.The base station 320 further has software 321 stored internally oraccessible via an external connection.

The communication system 300 further includes the UE 330 alreadyreferred to. Its hardware 335 may include a radio interface 337configured to set up and maintain a wireless connection 370 with a basestation serving a coverage area in which the UE 330 is currentlylocated. The hardware 335 of the UE 330 further includes processingcircuitry 338, which may comprise one or more programmable processors,application-specific integrated circuits, field programmable gate arraysor combinations of these (not shown) adapted to execute instructions.The UE 330 further comprises software 331, which is stored in oraccessible by the UE 330 and executable by the processing circuitry 338.The software 331 may optionally include a client application 332. Theclient application 332 may be operable to provide a service to a humanor non-human user via the UE 330, with the support of the host computer310. In the host computer 310, an executing host application 312 maycommunicate with the executing client application 332 via the OTTconnection 350 terminating at the UE 330 and the host computer 310. Inproviding the service to the user, the client application 332 mayreceive request data from the host application 312 and provide user datain response to the request data. The OTT connection 350 may transferboth the request data and the user data. The client application 332 mayinteract with the user to generate the user data that it provides.

It is noted that the host computer 310, base station 320 and UE 330illustrated in FIG. 3 may be identical to the host computer 230, one ofthe base stations 212 a, 212 b, 212 c and one of the UEs 291, 292 ofFIG. 2 , respectively. This is to say, the inner workings of theseentities may be as shown in FIG. 3 and independently, the surroundingnetwork topology may be that of FIG. 2 .

In FIG. 3 , the OTT connection 350 has been drawn abstractly toillustrate the communication between the host computer 310 and the useequipment 330 via the base station 320, without explicit reference toany intermediary devices and the precise routing of messages via thesedevices. Network infrastructure may determine the routing, which it maybe configured to hide from the UE 330 or from the service provideroperating the host computer 310, or both. While the OTT connection 350is active, the network infrastructure may further take decisions bywhich it dynamically changes the routing (e.g., on the basis of loadbalancing consideration or reconfiguration of the network).

As already outlined, a base station 320 dynamically schedules downlinktransmissions to UEs 330. The scheduling may be based on channel stateand quality information reports received from the UEs 330 on the PUCCHor a physical shared uplink channel or may be based on other factors.The channel state and quality information reports indicate theinstantaneous channel conditions as seen by the receiver. In each timeinterval (e.g., a LTE subframe or NR slot), the base station 320transmits DCI identifying the UEs that have been scheduled to receivedata in the current time interval and the resources on which the data isbeing transmitted to the scheduled UEs. The DCI is typically transmittedon a physical downlink control channel in an early portion of the timeinterval.

ARQ or HARQ is used to mitigate errors that occur during transmission ofdata on the DL. When the base station 320 indicates that a UE 330 isscheduled to receive a DL transmission, the UE 330 attempts to decodethe transmission and transmits an acknowledgement message to the basestation on the physical uplink control or shared channel. Theacknowledgement message informs the base station whether the data packetwas correctly received by the UE 330. The acknowledgement message may beeither a positively valued acknowledgement (ACK) indicating a successfuldecoding or a negatively valued acknowledgement (NACK) messageindicating a decoding failure. Based on the acknowledgement messagereceived from the UE 330, the base station 320 determines whether totransmit new data (ACK received) or to retransmit the previous data(NACK received). The introduction of an Acknowledgement ResourceIndicator (ARI) in connection with LTE carrier aggregation allowedexplicit allocation of resources for the acknowledgement message, sothat several UEs were able to share a pool of UL resourcessemi-statically reserved for this purpose without collisions. Theresource sharing was efficient since the average number of UEssimultaneously assigned resources on several DL carriers was small.

To initiate UL transmissions, a UE 330 may transmit a scheduling request(SR) to a base station 320 on the PUCCH when it has data to send but novalid uplink grant. The base station 320 allocates uplink resourcesresponsive to the scheduling requests and transmits a scheduling grantto the UE 330 on a physical DL control channel. When the data isreceived or no data arrives in the allocated uplink resources, the basestation 320 may transmit ACK/NACK signaling to the UE 330 on a DLchannel to indicate whether the data is received correctly. As analternative to ACK/NACK signaling, the base station 320 may schedule theUE 330 to resend the same UL data.

Returning to DL transmissions, NR may, as noted, support a large numberof PUCCH formats with different UL resource requirements. In thiscontext, although a resource may be referenced by a single resourceindex, it may be defined by a combination or one or more of time,frequency, phase rotation, orthogonal cover code (OCC). Additionally oralternatively, cyclic shift, starting symbol, duration (in number ofsymbols) and/or bandwidth (in number of physical resource blocks) may beconfigured for a resource. A choice of one of the indicated UL resourcesby the UE 330 may represent an acknowledgement feedback value, such aspositive or negative acknowledgement. Optionally, the acknowledgementfeedback value may be combined with a restriction to a specific portionof the DL transmission (this may allow differently valuedacknowledgements to be sent for different portions of the DLtransmission) and/or further information, such as a scheduling request,and different degrees of bundling and multiplexing may be applied. As aresult of these or similar factors, which are absent in such earliercommunication systems where the acknowledgement feedback is of constantlength, the number of distinct allocable UL resources may vary betweendifferent operating conditions, leading to a considerable gap betweenthe minimum and maximum number of required ART values. Therefore,embodiments herein may need to distinguish between different operatingconditions or between groups of operating conditions for which theacknowledgment feedback length is constant within each group.

A straightforward way to accommodate the full range of ARI values wouldbe to allow ARI more resources within DCI. This however would add aconstant signaling overhead corresponding to the worst case—the mostcomprehensive set of acknowledgement feedback values—also in situationswhere this is not needed, Instead, example embodiments herein propose apersistent ARI which is interpreted in view of a current operationalstate of the communication network.

More precisely and in accordance with an example embodiment, FIG. 6illustrates a method implemented in the UE 330.

In a first step 610, the UE 330 is configured with at least twocollections of UL resources to be used for transmitting, controlinformation to the communication network 300. On a network level, theconfiguration may have the effect that the collections of UL resourcesare reserved for transmitting control information. The collections ofUL, resources may be understood as a pool of resources that may beshared, in accordance with the ART, between the UEs currently operatingin the system.

In a second step 620, the UE 330 receives an assignment of radioresources to be used for receiving a DL transmission from the basestation 320.

In a third step 630, the UE 330 receives an ARI indicating one of theconfigured collections of UL resources to be used for transmittingcontrol information associated with the DL transmission. The ARI or theconfigured collection of UL resource may optionally define an explicittime position of the UL resources; alternatively, the time position ofthe UL resources is relative to the time position of the DL resources tobe used for the DL transmission, such as being located a predefinednumber of slots later in time.

In a fourth step 640, the UE 330 uses at least a subset of the indicatedcollection of UL resources to transmit the control informationassociated with the DL transmission to the base station 320. Moreprecisely, the indicated collection of UL resources comprises aplurality of selectable UL resource sets, from which the UE 330transmits an UL resource set corresponding to an operational state ofthe communication network.

Therefore, even if two operational modes differ in terms of theirrequirements for UL resources for control information, there is no needto introduce separate ARI values for the two operational modes. Instead,the meaning of a signaled ARI value wilt depend on the operational modeof the communication network 300. If the UE 330 is aware of the currentoperational mode, this implies that an amount of signaling overhead canbe left out. For instance, the UE 330 can become aware of the currentoperation mode by receiving semi-static or dynamic signaling that isseparate from the ARI, or by ascertaining a value of an internalvariable reflecting a previous configuration message, or by consideringoperational aspects of the network 300 that reveal the operational modeimplicitly. Instead, the UE 330 may determine implicitly based on theoperational mode what resources an ART value refers to. This said, eventhough a given ARI value may be reinterpreted as the operational modechanges, there is a need for two or more distinct ARI values if separateresources are to be allocated to two or more UEs contemporaneously.

The possible overhead reduction will be illustrated by a comparisonbetween a reference implementation, where ARI values are unique acrossoperational modes, and an implementation according to an exampleembodiment. In below Tables 1 and 2, ARI values are explicit, Rn (n=0, .. . , 16) represent resource indices, whereas M1 and M2 represent twooperational modes of the communication system.

TABLE 1 Reference implementation Used in ARI UL resources indicated ULresources indicated operational value in operational mode M1 inoperational mode M2 modes 000 R0, R1, R2, R3 R0, R1, R2, R3 M1 001 R4,R5, R6, R7 R4, R5, R6, R7 M1 010 R8, R9, R10, R11 R8, R9, R10, R11 M1011 R12, R13, R14, R15 R12, R13, R14, R15 M1 100 R0, R1 R0, R1 M2 101R4, R5 R4, R5 M2 110 R8, R9 R8, R9 M2 111 R12, R13 R12, R13 M2

Table 1 illustrates an implementation where the UE's interpretation ofthe ARI values is independent of the operational mode of thecommunication system 300. In practice, ARI values “000”, “001”, “010”and “011” are not expected in operational mode M2. Similarly, ARI values“100”, “101”, “110” and “111” normally would not be used in operationalmode M1.

TABLE 2 Exampile configuration I Used in ARI UL resources indicated ULresources indicated operational value in operational mode M1 inoperational mode M2 modes 00 R0, R1, R2, R3 R0, R1 M1, M2 01 R4, R5, R6,R7 R4, R5 M1, M2 10 R8, R9, R10, R11 R8, R9 M1, M2 11 R12, R13, R14, R15R12, R13 M1, M2

Because a reduced set of control information values is defined foroperational mode M2, each ARI value used in that operational modeindicates a smaller set of UL resources. Further UL resource sets {R0,R1, R2, R3} and {R0, R1} cannot be selected in the same operationalmode, not even by different UEs. Accordingly, these UL resource sets maybe addressed using a common ARI value, which is here fixed to “00”, Inthe example, the example embodiment reduces the necessary ARI payloadfrom three to two bits.

Phrased in another way, the signaled ARI value “00” has a basic meaning(e.g., {R0, R1, R2, R3}) which is overlaid with one or more furthermeanings (e.g., {R0, R1}) that apply when the communication system is ina particular operational mode or modes.

In accordance with an example embodiment, FIG. 7 illustrates a methodimplemented in the base station 320.

In a first step 710, the base station 320 obtains a configuration of atleast two collections of UL resources to be used for receiving controlinformation from user equipments in coverage of the communicationnetwork. Normally, the configuration is not addressed to a particular UEbut to all UE operating in a portion of the network.

In a second step 720, the base station 320 assigns radio resources to beused for transmitting a DL transmission to a UE 330. In implementations,the configuration and the assignment may differ in scope insofar as theconfiguration applies for all UEs operating in coverage of (a portionof) the communication network, whereas a DL assignment is typicallyaddressed to a particular one UE.

In a third step 730, the base station 320 transmits an ARI to the userequipment. The ARI may indicate one of the configured collections of ULresources to be used for receiving control information associated withthe DL transmission. As noted for step 630 (FIG. 6 ), the UL resourceshave an implicit time position (such as a constant separation) or anexplicit time position (such as a signaled slot or symbol index).

In a fourth step 740, the base station 320 uses at least a subset of theindicated collection of UL resources to receive the control informationfrom the UE 330. In this example embodiment, the indicated collection ofUL resources comprises a plurality of selectable UL resource sets andthe control information is received on one of the UL resource sets whichcorresponds to an operational state of the communication network. Asexplained above with reference to FIG. 7 , this has advantages at leastfrom the point of view of limiting signaling overhead.

A number of further developments of the example embodiments illustratedby FIGS. 6 and 7 will now be discussed. It is emphasized that thefeatures recited in the context of these further developments are alsouseful on their own and may be practiced autonomously, independently ofthe related basic embodiments.

The UE 330 may receive and attempt to decode the DL transmission controlinformation, wherein the control information is determined based on thedecoding success. Alternatively or additionally, the control informationmay comprise a request for UL transmission resources and/or a result ofa measurement performed by the UE 330. In particular, the controlinformation, which the UE 330 transmits and the base station 320receives, may comprise acknowledgement information associated with theDL transmission, such as ARQ or HARQ feedback.

In an example embodiment, the selectable sets of UL resources in theindicated collection of UL resources differ with respect to theircardinality. In particular, two selectable sets of UL resources maycomprise different numbers of UL resources. The number of UL resourcesavailable for the control information may influence the granularity ofthe information carried. For example, in an operational mode where eachUL resource set comprises relatively fewer UL resources, HARQ feedbackmay be sent on the level of a transport block comprising pluralcodewords, whereas in an operational mode with relatively more ULresources per UL resource set, HARQ feedback may be provided on thelevel of each codeword making up the transport block. In the lattercase, requested retransmissions may be limited to the codewords forwhich decoding has failed. This property may apply also for theselectable sets of UL resources in other collections of UL resourcesthan the indicated collection.

In an example embodiment, the indicated collection of UL resources has afirst UL resource set which comprises UL resources in addition to thoseof a second UL resource set. Alternatively or additionally, the secondUL resource set in the indicated collection of UL resources may be asubset of the first UL resource set. In particular, the second ULresource set may be a proper subset of the first UL resource set. The ULresource sets illustrated in Table 2 have these properties. Here, thecollections of UL resources correspond to the rows of the table, and ULresource sets within one collection correspond to different columns of arow. In the collection indicated by ARI value “10”, a first UL resourceset in the sense of this paragraph may be {R8, R9, R10, R11}, whichcorresponds to operational mode M1, and a second UL resource set may be{R8, R9}, which corresponds to operational mode M2.

In an example embodiment, the operational states representacknowledgement feedback modes or HARQ feedback modes. Anacknowledgement feedback mode may be a common setting of thecommunication network 300 and user equipments 330 in coverage thereof.An acknowledgement feedback mode may be associated with an agreement orcommon understanding between a user equipment 330 and a base station 320as to what acknowledgement messages can be communicated. The agreementmay be in the form of a table associating a signaled value (asrepresented by a code, a sequence, or an UL resource) with a meaning inthe acknowledgement or HARQ context. Example meanings may be: apositively or negatively valued acknowledgement (ACK or NACK) and/or arestriction of the acknowledgement to a specific portion of the DLtransmission and/or further information, such as a scheduling request.Two acknowledgement modes may differ with respect to the size of such atable or, expressed more generally, with respect to the granularity ofthe acknowledgement signaling. An acknowledgement feedback mode withrelatively more granular (e.g., relatively coarser) signaling—hence,fewer available meanings—may be referred to as a compressedacknowledgement feedback mode. With reference to the first and second ULresource sets discussed and exemplified in the preceding paragraph, thesecond UL resource set (which has smaller cardinality) may be employedin the compressed acknowledgement feedback mode, whereas the first ULresource set (which has greater cardinality) may be employed in anon-compressed mode, referred to as a normal acknowledgement feedbackmode.

In this context, whether the normal or the compressed acknowledgementfeedback mode is currently applicable may be or have been explicitlysignaled or may be derivable from other parameters accessible to the UE330 and base station 320. The responsibility for initiating a transitionbetween acknowledgement feedback modes may lie with the UE 330, the basestation 320 or another node of the communication network 300.

Further, the communication network 300 may be operable in more than twoacknowledgement feedback modes. At least some of the modes may differwith respect to the cardinality or size of the corresponding UL resourcesets in the collection of UL resources. The acknowledgement feedbackmodes may be ordered sequentially, so that a transition may be signaledincrementally, e.g., by a step ‘up’ or ‘down’ in relation to the currentmode.

In an example embodiment, the collections of UL resources are configuredin such manner that each collection comprises at least two selectable ULresource sets. The selectable UL resource sets may correspond torespective operational modes. Such a configuration is illustrated inTable 2 above. Configuring the collections of UL resources in thismanner may have the advantageous effect that a transition between theoperational modes is possible regardless of the collection indicated bythe ARI. Put differently, the entity responsible for initiating atransition between operational modes need not consider whether acollection of UL resources is being indicated by ARI or may be expectedto be indicated by ARI in the near future.

In an example embodiment, the configuration of the collection of ULresources reaches the UE 330 by semi-static signaling, such as RadioResource Control (RRC) signaling. If the base station 320 is responsiblefor configuring the collection of UL resources, it may signal theconfiguration semi-statically to the UE 330. If instead a differententity of the communication network 300 is responsible for configuringthe collection of UL resources, then both the UE 330 and the basestation 320 may receive semi-static signaling indicative of theconfiguration.

In an example embodiment, the ARI is transmitted in a message comprisingadditional information. In particular, the ARI may be transmitted in amessage also containing the DL assignment. The message may be a DCImessage. The DCI message may be transmitted from the base station 320 tothe UE 330 on a physical DL control channel.

In an example embodiment, the method illustrated in FIG. 6 furthercomprises the UE 330 determining an operational mode of thecommunication network 330. Based on the operational mode that currentlyapplies (or which will apply or is expected to apply when the assignedDL transmission is to be received by the UE 330), the UE 330 selects aUL resource set to be used for transmitting the control information tothe communication network 300.

In an example embodiment, the fact that the UL resource setscorresponding to different operational modes differ with respect totheir cardinality or size is utilized by the base station 320. Forexample, in an operational mode corresponding to relatively smaller ULresources sets, a larger number of UEs can be allowed to transmitcontrol information. As a consequence, more UEs can be scheduledsimultaneously. As illustrated by Table 2, UL resources R2, R3, R6, R7,R10, R11, R14 and R15 are not used in operational mode M2. If athree-bit ARI representation is used, one may configure the collectionsof UL resources in the way illustrated by Table 3.

TABLE 3 Example configuration II Used in ARI UL resources indicated ULresources indicated operational value in operational mode M1 inoperational mode M2 modes 000 R0, R1, R2, R3 R0, R1 M1, M2 001 R4, R5,R6, R7 R4, R5 M1, M2 010 R8, R9, R10, R11 R8, R9 M1, M2 011 R12, R13,R14, R15 R12, R13 M1, M2 100 R0, R1, R2, R3 R2, R3 M1, M2 101 R4, R5,R6, R7 R6, R7 M1, M2 110 R8, R9, R10, R11 R10, R11 M1, M2 111 R12, R13,R14, R15 R14, R15 M1, M2

In operational mode M1, the UL resources corresponding to ARI values“000” and “100” are overlap—actually coincide—but in operational mode M2they are disjoint. The same is true, in the respective operationalmodes, for the UL resources corresponding to ARI values “001” and “101”;ARI values “010” and “110”; and ARI values “011” and “111”. Accordingly,while this configuration allows four simultaneous UEs to transmitcontrol information in operational mode M1, eight UEs may transmitsimultaneously in operational mode M2.

The base station 320 may utilize this for the benefit of networkperformance by assigning respective radio resources to be used fortransmitting DL transmissions to a UE 291 and a further UE 292. The basestation 320 then transmits an ARI to the further user equipment 292indicating a different one of the configured collections of UL resourcesto be used for receiving control information associated with the DLtransmission to the further user equipment. The base station 320 doesthis in such manner that, in the indicated collection of UL resources,the respective UL resource sets corresponding to a current operationalstate of the communication network are disjoint. This represents aperformance gain if resource sets corresponding to at least onenon-current operational state of the communication network areoverlapping.

The wireless connection 370 between the UE 330 and the base station 320is in accordance with the teachings of the embodiments describedthroughout this disclosure and FIGS. 6 and 7 in particular. One or moreof the various embodiments improve the performance of OTT servicesprovided to the UE 330 using the OTT connection 350, in which thewireless connection 370 forms the last segment. More precisely, theteachings of these embodiments may improve the spectrum efficiency andpeak capacity of the network 300 by reducing the signaling overhead.This may provide benefits such as larger data capacity, lower risk ofnetwork congestion and/or extended battery lifetime.

A measurement procedure may be provided for the purpose of monitoringdata rate, latency and other factors on which the one or moreembodiments improve. There may further be an optional networkfunctionality for reconfiguring the OTT connection 350 between the hostcomputer 310 and UE 330, in response to variations in the measurementresults. The measurement procedure and/or the network functionality forreconfiguring the OTT connection 350 may be implemented in the software311 of the host computer 310 or in the software 331 of the UE 330, orboth. In embodiments, sensors (not shown) may be deployed in or inassociation with communication devices through which the OTT connection350 passes; the sensors may participate in the measurement procedure bysupplying values of the monitored quantities exemplified above, orsupplying values of other physical quantities from which software 311,331 may compute or estimate the monitored quantities. The reconfiguringof the OTT connection 350 may include message format, retransmissionsettings, preferred routing etc.; the reconfiguring need not affect thebase station 320, and it may be unknown or imperceptible to the basestation 320. Such procedures and functionalities may be known andpracticed in the art. In certain embodiments, measurements may involveproprietary UE signaling facilitating the host computer's 310measurements of throughput, propagation times, latency and the like. Themeasurements may be implemented in that the software 311, 331 causesmessages to be transmitted, in particular empty or ‘dummy’ messages,using the OTT connection 350 while it monitors propagation times, errorsetc.

FIG. 4 is a flowchart illustrating a method implemented in acommunication system, in accordance with one embodiment. Thecommunication system includes a host computer, a base station and a UEwhich may be those described with reference to FIGS. 2 and 3 . Forsimplicity of the present disclosure, only drawing references to FIG. 4will be included in this section. In a first step 410 of the method, thehost computer provides user data. In an optional substep 411 of thefirst step 410, the host computer provides the user data by executing ahost application. In a second step 420, the host computer initiates atransmission carrying the user data to the UE. In an optional third step430, the base station transmits to the UE the user data which wascarried in the transmission that the host computer initiated, inaccordance with the method illustrated in FIG. 7 . In an optional fourthstep 440, the UE executes a client application associated with the hostapplication executed by the host computer.

FIG. 5 is a flowchart illustrating a method implemented in acommunication system, in accordance with one embodiment. Thecommunication system includes a host computer, a base station and a UEwhich may be those described with reference to FIGS. 2 and 3 . Forsimplicity of the present disclosure, only drawing references to FIG. 5will be included in this section. In a first step 510 of the method, thehost computer provides user data. In an optional substep (not shown) thehost computer provides the user data by executing a host application. Ina second step 520, the host computer initiates a transmission carryingthe user data to the UE. The transmission may pass via the base station,in accordance with the method illustrated in FIG. 7 . In an optionalthird step 530, the UE receives the user data carried in thetransmission, in accordance with the method illustrated in FIG. 6 .

Further Example Embodiments

1. A method of transmitting control information to a communicationnetwork (300), the method being implemented in a user equipment (330)and comprising:

being configured with at least two collections of uplink, UL, resourcesto be used for transmitting control information to the communicationnetwork;

receiving an assignment of radio resources to be used for receiving adownlink, DL, transmission from a base station (320) of thecommunication network;

receiving an acknowledgement resource indication, ARI, indicating one ofthe configured collections of UL resources to be used for transmittingcontrol information associated with the DL transmission; and

transmitting the control information to the base station on at least asubset of the indicated collection of UL resources,

wherein the indicated collection of UL resources comprises a pluralityof selectable UL resource sets and the control information istransmitted on one of the UL resource sets which corresponds to anoperational state of the communication network.

2. The method of embodiment 1, wherein the control information comprisesacknowledgement information associated with the DL transmission.

3. The method of embodiment 1 or 2, wherein, in the indicated collectionof UL resources, at least two of the selectable UL resource sets differwith respect to their cardinality.

4. The method of any of the preceding embodiments, wherein, in theindicated collection of UL resources, a first UL resource set comprisesUL resources in addition to those of a second UL resource set.

5. The method of any of the preceding embodiments, wherein, in theindicated collection of UL resources, a second UL resource set is asubset of a first UL resource set.

6. The method of embodiment 4 or 5, wherein:

the operational states represent acknowledgement feedback modes;

the first UL resource set corresponds to a regular acknowledgementfeedback mode; and

the second UL resource set corresponds to a compressed acknowledgementfeedback mode.

7. The method of any of the preceding embodiments, wherein eachconfigured collection of UL resources comprises two or more selectableUL resource sets.

8. The method of any of the preceding embodiments, wherein, in the ULresource set on which the control information is transmitted, each ULresource represents a positively or negatively valued acknowledgement,optionally combined with a restriction to a specific portion of the DLtransmission and/or further information.9. The method of embodiment 8, wherein the UL resources aredistinguishable by at least one of: time, frequency, code.10. The method of any of the preceding embodiments, wherein the userequipment is configured with the collections of UL resources bysemi-static signaling.11. The method of any of the preceding embodiments, further comprising:

determining the operational mode of the communication network andselecting, based thereon, the UL resource set to be used fortransmitting the control information to the communication network.

12. The method of any of the preceding embodiments, wherein the ARI isreceived in a message comprising additional information.

13. The method of embodiment 12, wherein said message comprises the ARIand the assignment.

14. A user equipment (330) comprising a radio interface (337) andprocessing circuitry (338) configured to:

allow the UE to be configured with at least two collections of uplink,UL, resources to be used for transmitting control information to thecommunication network;

receive an assignment of radio resources to be used for receiving adownlink, DL, transmission from a base station (320) of thecommunication network;

receive an acknowledgement resource indication, ARI, indicating one ofthe configured collections of UL resources to be used for transmittingcontrol information associated with the DL transmission; and

transmit the control information to the base station on at least asubset of the indicated collection of UL resources,

wherein the indicated collection of UL resources comprises a pluralityof selectable UL resource sets and the control information istransmitted on one of the UL resource sets which corresponds to anoperational state of the communication network.

15. The user equipment of embodiment 14, wherein the processingcircuitry is further configured to perform the method of any ofembodiments 2 to 13.

16. A method of receiving control information at a base station (212;320) of a communication network (211; 330), the method comprising:

obtaining a configuration of at least two collections of uplink, UL,resources to be used for receiving control information from userequipments in coverage of the communication network;

assigning radio resources to be used for transmitting a downlink, DL,transmission to a user equipment (291; 330);

transmitting an acknowledgement resource indication, ARI, to the userequipment, the ARI indicating one of the configured collections of ULresources to be used for receiving control information associated withthe DL transmission; and

receiving the control information from the user equipment on at least asubset of the indicated collection of UL resources,

wherein the indicated collection of UL resources comprises a pluralityof selectable UL resource sets and the control information is receivedon one of the UL resource sets which corresponds to an operational stateof the communication network.

17. The method of embodiment 16, wherein the obtaining of aconfiguration of the collections of UL resources comprises determiningthe configuration.

18. The method of embodiment 17, wherein the obtaining of aconfiguration of the collections of UL resources further comprisestransmitting semi-static signaling to the user equipment.

19. The method of embodiment 16, wherein the obtaining of aconfiguration of the collections of UL resources comprises receivinginformation from a different node of the communication network.

20. The method of any of embodiments 16 to 19, further comprising:

assigning radio resources to be used for transmitting a DL transmissionto a further user equipment (292); and

transmitting an ARI to the further user equipment, the ARI indicating adifferent one of the configured collections of UL resources to be usedfor receiving control information associated with the DL transmission tothe further user equipment,

wherein, in the indicated collection of UL resources, the respective ULresource sets corresponding to a current operational state of thecommunication network are disjoint.

21. The method of embodiment 20, wherein, in the indicated collectionsof UL resources, respective UL resource sets corresponding to at leastone non-current operational state of the communication network areoverlapping.

22. The method of any of embodiments 16 to 21, wherein the controlinformation comprises acknowledgement information associated with the DLtransmission.

23. The method of any of embodiments 16 to 22, wherein, in the indicatedcollection of UL resources, at least two of the selectable UL resourcesets differ with respect to their cardinality.

24. The method of any of embodiments 16 to 23, wherein, in the indicatedcollection of UL resources, a first UL resource set comprises ULresources in addition to those of a second UL resource set.

25. The method of any of embodiments 16 to 24, wherein, in the indicatedcollection of UL resources, a second UL resource set is a subset of afirst UL resource set.

26. The method of embodiment 24 or 25, wherein:

the operational states represent acknowledgement feedback modes;

the first UL resource set corresponds to a regular acknowledgementfeedback mode; and

the second UL resource set corresponds to a compressed acknowledgementfeedback mode.

27. The method of any of embodiments 16 to 26, wherein each configuredcollection of UL resources comprises two or more selectable UL resourcesets.

28. The method of any of embodiments 16 to 27, wherein, in the ULresource set on which the control information is transmitted, each ULresource represents a positively or negatively valued acknowledgement,optionally combined with a restriction to a specific portion of the DLtransmission and/or further information.29. The method of embodiment 28, wherein the UL resources aredistinguishable by at least one of: time, frequency, code.30. The method of any of embodiments 16 to 29, further comprising:

determining the operational state of the communication network andselecting, based thereon, the UL resource set to be used for receivingthe control information.

31. The method of any of embodiments 16 to 30, wherein the ARI istransmitted in a message comprising additional information.

32. The method of embodiment 31, wherein said message comprises the ARIand the assignment.

33. A base station (320) for operating in a communication network (300)comprising a radio interface (327) and processing circuitry (328)configured to:

obtain a configuration of at least two collections of uplink, UL,resources to be used for receiving control information from userequipments in coverage of the communication network;

assign radio resources to be used for transmitting a downlink, DL,transmission to a user equipment (330);

transmit an acknowledgement resource indication, ARI, to the userequipment, the ARI indicating one of the configured collections of ULresources to be used for receiving control information associated withthe DL transmission; and

receive the control information from the user equipment on at least asubset of the indicated collection of UL resources,

wherein the indicated collection of UL resources comprises a pluralityof selectable UL resource sets and the control information is receivedon one of the UL resource sets which corresponds to an operational stateof the communication network.

34. The base station of embodiment 33, wherein the processing circuitryis further configured to perform an of the methods of embodiments 17 to32.

35. A computer program comprising computer-readable instructions forcausing a programmable processor to perform the method of any ofembodiments 1 to 13 or any of embodiments 16 to 32.

36. A computer program product comprising a computer-readable mediumstoring the computer program of embodiment 35.

Embodiments herein also include a computer program comprisinginstructions which, when executed by at least one processor of a UE or abase station, cause the UE or base station to carry out the methodsshown in FIGS. 4 to 7 , or variations thereof. In one or moreembodiments, a computer-readable medium storing the computer program isembodied as communication media (or transitory media, such as anelectronic signal, optical signal, radio signal) or storage media (ornon-transitory media) or a combination thereof. The term storage mediaincludes both volatile and nonvolatile, removable and non-removablemedia implemented in any method or technology for storage ofinformation; storage media includes but is not limited to RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks or other optical disk storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other medium which stores the desired information and isaccessible by a computer. In at least one embodiment, a communicationnode or other apparatus is configured to perform the operations orfunctions disclosed herein, based at least in part on node processingcircuitry executing computer program instructions stored in anon-transitory computer-readable medium.

The present invention may, of course, be carried out in other ways thanthose specifically set forth herein without departing from essentialcharacteristics of the invention. The present embodiments are to beconsidered in all respects as illustrative and not restrictive, and allchanges coming within the meaning and equivalency range of the appendedclaims are intended to be embraced therein.

The invention claimed is:
 1. A method of transmitting controlinformation to a communication network, the method being implemented ina user equipment (UE), the method comprising: receiving, via radioresource control signaling, a configuration of at least two collectionsof uplink (UL) resources to be used for transmitting control informationto the communication network; receiving an assignment of radio resourcesto be used for receiving a downlink (DL) transmission from a basestation of the communication network; receiving an acknowledgementresource indication (ARI) indicating one of the configured collectionsof UL resources to be used for transmitting control informationassociated with the DL transmission; and transmitting the controlinformation associated with the DL transmission to the base station onat least a subset of the indicated collection of UL resources, whereinthe control information associated with the DL transmission comprisesacknowledgement information associated with the DL transmission, whereinthe acknowledgement information is hybrid automatic repeat request(HARQ) feedback, wherein the indicated collection of UL resourcescomprises a plurality of selectable UL resource sets, the plurality ofselectable UL resource sets including a first UL resource set for use ina first acknowledgement feedback mode of the communication network and asecond UL resource set for use in a second acknowledgement feedback modeof the communication network, and wherein the control informationassociated with the DL transmission is transmitted on the one of theselectable UL resource sets which corresponds to the currentacknowledgement feedback mode of the communication network, wherein, inthe indicated collection of UL resources, the second UL resource setcomprises the UL resources of the first UL resource set and UL resourcesin addition to those of the first UL resource set.
 2. The method ofclaim 1, further comprising: determining the acknowledgement feedbackmode of the communication network and selecting, based thereon, the ULresource set to be used for transmitting the control informationassociated with the DL transmission.
 3. The method of claim 1, whereinthe ARI is received in a downlink control information (DCI) messagewhich also comprises the assignment.
 4. A user equipment (UE) comprisinga radio interface and processing circuitry configured to cause the UEto: receive, via radio resource control signaling, a configuration of atleast two collections of uplink (UL) resources to be used fortransmitting control information to a communication network; receive anassignment of radio resources to be used for receiving a downlink (DL)transmission from a base station of the communication network; receivean acknowledgement resource indication (ARI) indicating one of theconfigured collections of UL resources to be used for transmittingcontrol information associated with the DL transmission; and transmitthe control information associated with the DL transmission to the basestation on at least a subset of the indicated collection of ULresources, wherein the control information associated with the DLtransmission comprises acknowledgement information associated with theDL transmission, wherein the acknowledgement information is hybridautomatic repeat request (HARQ) feedback, wherein the indicatedcollection of UL resources comprises a plurality of selectable ULresource sets, the plurality of selectable UL resource sets including afirst UL resource set for use in a first acknowledgement feedback modeof the communication network and a second UL resource set for use in asecond acknowledgement feedback mode of the communication network, andwherein the control information associated with the DL transmission istransmitted on the one of the selectable UL resource sets whichcorresponds to the current acknowledgement feedback mode of thecommunication network, wherein, in the indicated collection of ULresources, the second UL resource set comprises the UL resources of thefirst UL resource set and UL resources in addition to those of the firstUL resource set.
 5. The UE of claim 4, wherein the processing circuitryis configured to cause the UE to: determine the acknowledgement feedbackmode of the communication network and select, based thereon, the ULresource set to be used for transmitting the control informationassociated with the DL transmission.
 6. The UE of claim 4, wherein theprocessing circuitry is configured to cause the UE to receive the ARI ina downlink control information (DCI) message which also comprises theassignment.
 7. A method of receiving control information at a basestation of a communication network, the method comprising: obtaining aconfiguration of at least two collections of uplink (UL) resources to beused for receiving control information from user equipments in coverageof the communication network; signaling the configuration to a userequipment (UE), via radio resource control signaling; assigning radioresources to be used for transmitting a downlink (DL) transmission tothe UE; transmitting an acknowledgement resource indication (ARI) to theUE, the ARI indicating one of the configured collections of UL resourcesto be used for receiving control information associated with the DLtransmission; and receiving the control information associated with theDL transmission from the UE on at least a subset of the indicatedcollection of UL resources, wherein the control information associatedwith the DL transmission comprises acknowledgement informationassociated with the DL transmission, wherein the acknowledgementinformation is hybrid automatic repeat request (HARQ) feedback, whereinthe indicated collection of UL resources comprises a plurality ofselectable UL resource sets, the plurality of selectable UL resourcesets including a first UL resource set for use in a firstacknowledgement feedback mode of the communication network and a secondUL resource set for use in a second acknowledgement feedback mode of thecommunication network, and wherein the control information associatedwith the DL transmission is received on the one of the selectable ULresource sets which corresponds to the current acknowledgement feedbackmode of the communication network, wherein, in the indicated collectionof UL resources, the second UL resource set comprises the UL resourcesof the first UL resource set and UL resources in addition to those ofthe first UL resource set.
 8. The method of claim 7, wherein theobtaining of the configuration of the collections of UL resourcescomprises determining the configuration.
 9. The method of claim 7,further comprising: determining the acknowledgement feedback mode of thecommunication network and selecting, based thereon, the UL resource setto be used for receiving the control information associated with the DLtransmission.
 10. The method of claim 7, wherein the ARI is transmittedin a downlink control information (DCI) message which also comprises theassignment of radio resources to be used for transmitting the DLtransmission to the UE.
 11. A base station for operating in acommunication network, the base station comprising a radio interface andprocessing circuitry configured to cause the base station to: obtain aconfiguration of at least two collections of uplink (UL) resources to beused for receiving control information from user equipments in coverageof the communication network; signal the configuration to a userequipment (UE), via radio resource control signaling; assign radioresources to be used for transmitting a downlink (DL) transmission tothe UE; transmit an acknowledgement resource indication (ARI), to theUE, the ARI indicating one of the configured collections of UL resourcesto be used for receiving control information associated with the DLtransmission; and receive the control information associated with the DLtransmission from the UE on at least a subset of the indicatedcollection of UL resources, wherein the control information associatedwith the DL transmission comprises acknowledgement informationassociated with the DL transmission, wherein the acknowledgementinformation is hybrid automatic repeat request (HARQ) feedback, whereinthe indicated collection of UL resources comprises a plurality ofselectable UL resource sets, the plurality of selectable UL resourcesets including a first UL resource set for use in a firstacknowledgement feedback mode of the communication network and a secondUL resource set for use in a second acknowledgement feedback mode of thecommunication network, and wherein the control information associatedwith the DL transmission is received on the one of the selectable ULresource sets which corresponds to the current acknowledgement feedbackmode of the communication network, wherein, in the indicated collectionof UL resources, the second UL resource set comprises the UL resourcesof the first UL resource set and UL resources in addition to those ofthe first UL resource set.
 12. The base station of claim 11, wherein thebase station is configured to obtain the configuration of thecollections of UL resources by determining the configuration.
 13. Thebase station of claim 11, wherein the processing circuitry is configuredto cause the UE to: determine the acknowledgement feedback mode of thecommunication network and select, based thereon, the UL resource set tobe used for receiving the control information associated with the DLtransmission.
 14. The base station of claim 11, wherein the processingcircuitry is configured to cause the base station to transmit the ARI ina downlink control information (DCI) message which also comprises theassignment of radio resources to be used for transmitting the DLtransmission to the UE.